<let/open = true/>
<let/list = [1,2,3]/>
<ul hidden=!open>
  <for|x| of=list by(x) { return x }>
    <li>${x}</li>
  </for>
</ul>
<button#toggle onClick() { open=!open }>Toggle</button>
<button#reverse onClick() { list = [].concat(list).reverse() }>Reverse</button>